PROJECT SUMMARY Eating disorders (EDs) are serious mental illnesses afflicting approximately 5% of women. Anorexia nervosa (AN) is an ED that includes distortions of body shape and size and restriction of calories resulting in insufficient nutrition. Bulimia nervosa (BN) is an ED defined by an over-valuation of a thin body size which leads to dysfunctional eating behaviors, including restriction, binge eating, and purging. Both diseases are defined by altered beliefs about oneself, including problems of self-perception (body image distortions) and self-esteem. Previously, we have found neurobiological differences related to self-perception (medial prefrontal cortex and precuneus) and other-perception (temporoparietal junctions) and social self-evaluations (dorsal anterior cingulate, insula, medial prefrontal cortex) in EDs. Here, we will conduct a detailed analysis of self and other perception in a population of 40 women with AN, 40 women with BN, and 40 healthy women, using a series of complementary functional magnetic resonance imaging (fMRI) tasks in concert with clinical interviews, cognitive assessments, and self-report measures. The key goal of this project is to understand the neurobiological circuitry that mediates the core disturbances related to self-perception in EDs. Four different fMRI tasks have been included that evaluate complementary components of self and other perception. The Self-Tagging task assesses self-perception independent of social evaluations. The Social Identity with Values Task assesses self-perception and perspective-taking in the context of socially-defined values. The Affective Trust Game examines how a specific relationship with another individual develops, by measuring behavioral and neural responses during a series of economic interactions with a specific other person. The Affective Ultimatum game examines how behavior, neural activations, and moods change as subjects play a game that includes shifts of society, created with monetary exchanges. This game will allow a neural, mechanistic examination for a pathological trait believed to be related to pathogenesis of BN: disordered eating behaviors in BN are associated with exposure to different social norms such as the ?thin-ideal? for female shape/size. In addition, three of these tasks consider differences for both positive and negative self-relevant stimuli, allowing us to evaluate how valence might contribute to neurobiological dysfunctions in self and other perception in EDs. We will use dynamic causal modeling (DCM), a method to examine the timing, directionality, and interactions occurring between different neural regions, building a network model of how dysfunctions in self-knowledge contribute to EDs. Core symptoms in adult EDs including feeding symptoms, body preoccupations, self-esteem, anxiety, and depression will be correlated with differences in the self/other neural circuitry. At conclusion of this study, we will have a biomarker understanding of the neurocircuitry for self/other perception and how these differences may contribute to the pathophysiology of EDs.